1. Field of the Invention
This invention relates, generally, to paper feeding accessory machines. More particularly, it relates to an envelope hopper of the type that is automatically replenished so that it remains substantially full and consistent in weight even when dispensing envelopes at a high rate of speed.
2 Description of the Prior Art
High volume machines for opening envelopes, inserting sheets into them, and closing the envelopes are in widespread use. These machines include envelope hoppers for storing a supply of envelopes to be opened. There are three primary types of envelope hoppers. One type includes a reciprocating horizontal support plate, or shuttle, positioned at the bottom of a hopper that discharges one envelope with each reciprocation. The envelopes in this type of hopper are disposed in a horizontal plane when in the hopper. Another type of hopper discharges envelopes when they are vertically disposed. A third type has continuous moving belts and relies on friction.
One of the most efficient means for filling an envelope hopper includes a horizontally disposed, elongate conveyor because large quantities of envelopes can be placed on the conveyor, thereby reducing the number of times a machine operator must replenish the envelope supply. Significantly, the conveyor supports the weight of the envelopes along its length. Accordingly, such arrangement is preferable to those prior art hoppers where a tall vertical stack of envelopes is placed in the hopper. A tall stack exerts significant weight upon the lowermost envelope. That is undesirable because the lowermost envelope is discharged from the hopper by an envelope discharging means which may require readjustment as the stack shortens and pressure on said discharging means reduces.
When an elongate, horizontal conveyor is used to support a long queue of envelopes entering a hopper, the bottom of the hopper is positioned in a horizontal plane a few inches below the conveyor so that the envelopes entering the hopper at the leading end of the conveyor follow a downwardly turned path of travel having a radius of curvature somewhat like that of water flowing over a low waterfall. More particularly, each envelope is in a vertical or substantially vertical disposition while on the conveyor, ie. , on its bottom longitudinal edge, with its flap facing away from the hopper toward which it is traveling. Upon arriving at an empty hopper, the first envelopes fall thereinto on their address-carrying sides, ie. , with their flaps facing upwardly. Thus, the envelopes in the hopper are in a horizontal plane. An operator will typically position the first supply of envelopes in the hopper so that said envelopes need not fall thereinto. The uppermost edges of the envelopes entering the hopper collectively form a round, downwardly turned profile at the entrance of the hopper as new envelopes gradually enter the hopper, rotating from their vertical disposition to their horizontal disposition, as envelopes are discharged from the bottom of the hopper by a suitable envelope discharging means. The speed of the conveyor is timed to supply a new envelope to the top of the short stack of envelopes in the hopper each time an envelope is removed from the bottom of the hopper for transportation to an envelope-opening means.
In this way, the height of the stack of envelopes in the hopper remains constant when the machine is operating. Significantly, this maintains the weight on the lowermost envelope at a constant value, thereby ensuring maximal operation of the envelope-discharging means.
Dispensing vertically stacked envelopes at a high rate of speed from an envelope hopper in a sequential fashion is problematic because the envelopes easily become misaligned from one another as they follow the downwardly turned path of travel. The hopper can become jammed or misfed because it requires each envelope being discharged from the bottom of the hopper to be in exactly the same position and orientation as the preceding envelope. It is customary in the industry to rely on a machine operator to jiggle or jostle the envelopes from time to time to maintain their alignment, but this labor-intensive solution is unacceptable. What is needed, then, is an automated way of vibrating the envelopes in an envelope hopper so that no human intervention is required.
However, in view of the prior art in at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how the identified needs could be fulfilled.
The longstanding but heretofore unfulfilled need for an improvement to an envelope hopper that maintains the alignment of the envelopes therein substantially in the absence of machine operator intervention is now met by a new, useful, and nonobvious invention. The novel envelope hopper is of the type that is continually filled with envelopes by a suitable hopper filling means. The hopper filling means includes an elongate, horizontally disposed conveyor means. The envelope hopper is positioned in longitudinal alignment with the conveyor means at a leading end thereof. The envelope hopper is positioned in a plane below the conveyor means so that envelopes entering into the envelope hopper from the conveyor means follow a downwardly turned path of travel. The envelope hopper includes an outboard and inboard wall means that are transversely spaced apart from one another by a distance slightly greater than an envelope length and a front and back wall means that are longitudinally spaced apart from one another by a distance slightly greater than an envelope width. The envelope hopper is adapted to hold a vertical stack of envelopes therein. A vibrating means is provided for imparting a continuous vibration to a preselected part of the envelope hopper so that vertical alignment of the vertical stack is maintained. The vibrating means makes physical contact with the preselected part of the envelope hopper. The preselected part may be the outboard wall means, the inboard wall means, the front wall means, the back wall means, or any other suitable part of the hopper.
In one embodiment of the invention, a shuttle is positioned at a lowermost end of the envelope hopper for supporting envelopes that are vertically stacked in the envelope hopper. An envelope-engaging member is secured to an upward-facing side of the shuttle, and the shuttle is mounted for reciprocation between a retracted position and an extended position. Means are provided for continuously reciprocating the shuttle between its retracted and extended positions. The envelope-engaging member makes physical contact with the envelope hopper for each reciprocation of the shuttle. In this way, the reciprocation of the shuttle imparts a vibration to the envelope hopper that maintains the envelopes in their vertical alignment.
The envelope-engaging member may take the form of a wedge-shaped member that has a raised outboard end and a lowered inboard end.
In embodiments that do not include a horizontally-disposed shuttle, such as hoppers that have bottom-mounted suction cups that sequentially remove the lowermost envelopes from the hopper, a vibration means is applied to any of the walls or posts that collectively maintain the envelopes in their vertically stacked configuration.
A primary object of the invention is to provide an automated means for maintaining envelope alignment in an envelope hopper of the type that dispenses envelopes at a high rate.
A closely related object is to provide such means that can be retrofit onto an existing conventional hopper to minimize the expense of such automated means.
These and other important objects, advantages, and features of the invention will become clear as this description proceeds.
The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts that will be exemplified in the description set forth hereinafter and the scope of the invention will be indicated in the claims.